Automotive vehicle designers often desire a windshield wiping mechanism having a wiper which is positioned near or below the window cowl when not in operation, sometimes called a depressed park position. A wiper depressed park position is desirable for aesthetic purposes, as well as for preventing damage to the wipers when exposed to environmental conditions. Mechanisms for moving the wipers to the depressed park position typically do so by forcing a drive pin through which the motor drives the wipers to a radially altered position, as shown in U.S. Pat. No. 4,878,398 (Heinrich). Such mechanisms, however, do not allow for the possibility that snow, ice, slush, accumulated debris, or other obstructions may prevent the wipers from reaching the depressed park position when operation ceases. In such a circumstance, the motor may continue to drive the wipers to the depressed park position potentially resulting in damage to the motor and the wiper linkages.
Some windshield wiping mechanisms alter the wiping pattern, or range, in response to accumulated snow during windshield wiping operation, as shown in U.S. Pat. No. 5,179,760 (Abe). Such a mechanism does not provide variable depressed park capability but is merely directed to changing the wiper range during normal wiping operation.